Synergistic pre-emergent and post-emergent weed control compositions and methods of use thereof

ABSTRACT

Methods and compositions for synergistic pre-emergent and post-emergent weed control are disclosed. In particular, the present disclosure relates to an herbicidal composition comprising at least one pre-emergent herbicide and at least one post-emergent herbicide, wherein the pre-emergent herbicide and the post-emergent herbicide synergistically inhibit pre-emergent and post-emergent development of a weed. The disclosure further relates to herbicidal compositions comprising isoxaben, 2,4-D, mecoprop-P, and dicamba.

Methods and compositions for synergistic pre-emergent and post-emergentweed control are disclosed.

BACKGROUND

Herbicides generally can be classified into two broad categories basedon the time at which it is applied: pre-emergent herbicides andpost-emergent herbicides. Pre-emergent herbicides act by preventingemergence of seedlings and therefore are useful for preventing new weedgrowth from developing. Post-emergent herbicides, on the other hand, areeffective at eradicating fully developed weeds. Given the differentmechanisms of action and the developmental stages of the weeds in whichthey act, one would not expect pre-emergent and post-emergent herbicidesto have any effect on one another. Therefore, it was surprising todiscover that certain mixtures of pre-emergent and post-emergentherbicides synergistically enhance the pre-emergent and post-emergentherbicidal effects of one another, i.e. the activities of the mixturesare greater than the sum of the individual activities. Thus, anunforeseeable synergistic effect is present, and not just an addition ofactivities.

SUMMARY

The present disclosure relates to herbicidal compositions comprising atleast one pre-emergent herbicide and at least one post-emergentherbicide, wherein the pre-emergent herbicide and the post-emergentherbicide synergistically inhibit pre-emergent and post-emergentdevelopment of a weed. Exemplary compositions comprise at least onepre-emergent herbicide comprising at least one active ingredientselected from the group consisting of isoxaben and indaziflam; andwherein the at least one post-emergent herbicide comprises at least oneactive ingredient selected from the group consisting of: 2,4-D;mecoprop-P; dicamba; 2,4-DB; 2,4-DP; aminopyralid; atrazine;carfentrazone; chlorsulfuron; clopyralid; diflufenican; ethoxysulfuron;florasulam; fluoroxypyr; imazaquin; iodosulfuron; MCPA; metribuzin;metsulfuron methyl; penoxsulam; quinclorac; tembotrione; thiencarbazonemethyl; and triclopyr. Such compositions further may be selectedaccording to effectiveness at controlling a broadleaf weed selected fromthe group consisting of: plantain, including buckhorn plantain; clover,including white clover, red clover, and rabbitfoot clover; black medic;dandelion; henbit; pigweed; purslane; spurge; false dandelion; groundivy; wild garlic; and wild onion.

Further disclosed are herbicidal compositions comprising isoxaben;2,4-D; and mecoprop-P. These compositions preferably comprise from about0.2 to about 25 W/W % of isoxaben; from about 0.05 to about 35 W/W % of2,4-D; and from about 0.05 to about 20 W/W % of mecoprop-P. Morepreferably, these compositions comprise from about 2 to about 3 W/W % ofisoxaben; from about 3 to about 5 W/W % of 2,4-D; and from about 0.1 toabout 1 W/W % of mecoprop-P. Most preferably, these compositionscomprise from about 2.4 to about 2.9 W/W % of isoxaben; from about 3.50to about 4.32 W/W % of 2,4-D; and from about 0.7 to about 1.1 W/W % ofmecoprop-P. These compositions may further comprise dicamba, preferablycomprising from about 0.01 to about 25 W/W %, more preferably from about0.1 to about 0.8 W/W %, and most preferably from about 0.4 to about 0.5W/W % of dicamba.

Also disclosed are methods of controlling weed growth, comprisingadministering a composition comprising at least one pre-emergentherbicide and at least one post-emergent herbicide, wherein thepre-emergent herbicide and the post-emergent herbicide synergisticallyinhibit pre-emergent and post-emergent development of a weed.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows data compiled from a compilation of tests for pre-emergentsynergism of a composition comprising isoxaben; 2,4-D; mecoprop-P, anddicamba at full label dosage.

FIG. 2 shows data compiled from a compilation of tests for pre-emergentsynergism of a composition comprising isoxaben; 2,4-D; mecoprop-P, anddicamba at one-half and one-fifth of full label dosage.

FIG. 3 shows data compiled from a compilation of tests for post-emergentsynergism of a composition comprising isoxaben; 2,4-D; mecoprop-P, anddicamba at full label dosage.

FIG. 4 shows data compiled from a compilation of tests for post-emergentsynergism of a composition comprising isoxaben; 2,4-D; mecoprop-P, anddicamba at one-half and one-fifth of full label dosage.

DETAILED DESCRIPTION

Traditionally, pre-emergent and post-emergent herbicides have beenapplied in separate formulations at different times. Becausepre-emergent herbicides typically do not have any effect on weeds thathave already emerged, they must be applied in early spring or latesummer before weeds begin germinating and emerging. That is, whilepre-emergent herbicides are effective at preventing weed growth, theytypically are ineffective at killing established weeds. Likewise,post-emergent herbicides typically cannot be applied to any effect untilweeds have actually emerged. That is, while post-emergent herbicides areeffective at killing established weeds, they typically are ineffectiveat preventing weed growth.

Despite the fact that many of these pre-emergent and post-emergentherbicides have been known for some time, herbicidal compositionscomprising both pre-emergent and post-emergent herbicides are quiterare. Prior to 2009, the only commercially available product was ScottsTurf Builder Max Plus 2 Weed & Feed and Crabgrass Preventer, which haslimited potential for preventing emergence of broadleaf weeds.

Therefore, a need exists for effective herbicide formulations thatcombine pre-emergent herbicides and post-emergent herbicides, as well asmethods of using such herbicidal compositions. Such compositions andmethods are disclosed herein.

Further, given that pre-emergent and post-emergent herbicides act viadifferent mechanisms and at different times in the life cycle of a weed,a person having ordinary skill in the art would not expect apre-emergent herbicide to have any effect on a post-emergent herbicide,and vice versa. Nonetheless, it has been discovered that, in thecompositions disclosed herein, the pre-emergent herbicidessynergistically augment the activity of the post-emergent herbicides,and vice versa. Accordingly, compositions for controlling weed growthare disclosed, said compositions comprising at least one pre-emergentherbicide and at least one post-emergent herbicide, wherein thepre-emergent herbicide and the post-emergent herbicide synergisticallyinhibit pre-emergent and post-emergent development of a weed and methodsof use thereof.

As used herein, “pre-emergent herbicide” refers to an herbicide thatacts on newly germinating seedlings before they emerge. Exemplarypre-emergent herbicides useful in the compositions and methods disclosedherein include isoxaben and indaziflam.

Isoxaben is a benzamide compound of the HRAC Group L herbicides. It actsby inhibiting cellulose synthesis, thereby inhibiting cell wallformation and blocking emergence of seedlings. Isoxaben controls thebroadest spectrum of broadleaf weeds of commonly-used pre-emergentherbicides; can be used on all major turf types, including cool season(C3) turf types, e.g. Kentucky bluegrass, fescue, and ryegrass; lastsfor up to six months after application; and does not stain exteriorhardscapes.

Indaziflam belongs to the chemical class of alkylazines. It inhibitscell wall biosynthesis and acts on meristematic cell growth, therebyeffectively controlling a broad spectrum of weeds, including specieswhich are difficult to eliminate such as annual bluegrass, goosegrass,ryegrass and goosefoot. Indaziflam is an excellent mixing partner andcan be used either pre- or post-emergent in conjunction withpost-emergent herbicides. Another advantage of indaziflam is the lowapplication rate. Because of the long-lasting action and the broadspectrum of activity, the number of applications can be reduced.Indaziflam is particularly useful for warm season (C4) turf types, suchas bermudagrass, zoysia, St. Augustinegrass, and centipedegrass.

These compounds are effective at preventing emergence of a number ofweeds, including but not limited to the following broadleaf weeds:plantain, including buckhorn plantain; clover, including white clover,red clover, and rabbitfoot clover; black medic; dandelion; henbit;pigweed; purslane; spurge; false dandelion; ground ivy; wild garlic; andwild onion.

As used herein, “post-emergent herbicides” refers to herbicides that areactive only on emerged plants. Exemplary pre-emergent herbicides usefulin the compositions and methods disclosed herein include 2,4-D;mecoprop-P; dicamba; 2,4-DB; 2,4-DP; aminopyralid; atrazine;carfentrazone; chlorsulfuron; clopyralid; diflufenican; ethoxysulfuron;florasulam; fluoroxypyr; imazaquin; iodosulfuron; MCPA; metribuzin;metsulfuron methyl; penoxsulam; quinclorac; tembotrione; thiencarbazonemethyl; and triclopyr.

2,4-D is a synthetic auxin, which is a class of plant growth regulators.It is absorbed through the leaves and is translocated to the meristemsof the plant. Uncontrolled, unsustainable growth ensues, causing stemcurl-over, leaf withering, and eventual plant death.

mecoprop-P is a selective, hormone-type phenoxy herbicide. It is used onornamentals and sports turf, for forest site preparation, and ondrainage ditch banks for selective control of surface creeping broadleafweeds such as clovers, chickweed, lambsquarters, ivy, plantain andothers. It is also used on wheat, barley, and oats. Mecoprop is absorbedby plant leaves and translocated to the roots. It affects enzymeactivity and plant growth. It acts relatively slowly requiring three tofour weeks for control

Dicamba is an auxin analog, causing uncontrollable growth eventuallyleading to plant death.

2,4-D, mecoprop-P, and dicamba frequently are used in combination withone another, both in two-way and three-way post-emergent herbicides. Forexample, one commercially-available two-way herbicide is ScottsTurfbuilder Plus 2 Weed Control, which comprises 2,4-D and mecoprop-P.Exemplary three-way post-emergent herbicides include Bayer AdvancedSouthern Weed Killer for Lawns and PBI/Gordon's Trimec Growth RegulatorHerbicide, both of which comprise 2,4-D, mecoprop-P, and dicamba.

These post-emergent compounds, as well as the two-way and three-waypost-emergent formulations set forth above, are effective at killing anumber of established weeds, including but not limited to the followingbroadleaf weeds: plantain, including buckhorn plantain; clover,including white clover, red clover, and rabbitfoot clover; black medic;dandelion; henbit; pigweed; purslane; spurge; false dandelion; groundivy; wild garlic; and wild onion.

Preferred compositions comprise isoxaben; 2,4-D; and mecoprop-P. Thesecompositions preferably comprise from about 0.2 to about 25 W/W % ofisoxaben; from about 0.05 to about 35 W/W % of 2,4-D; and from about0.05 to about 20 W/W % of mecoprop-P. More preferably, thesecompositions comprise from about 2 to about 3 W/W % of isoxaben; fromabout 3 to about 5 W/W % of 2,4-D; and from about 0.1 to about 1 W/W %of mecoprop-P. Most preferably, these compositions comprise from about2.4 to about 2.9 W/W % of isoxaben; from about 3.50 to about 4.32 W/W %of 2,4-D; and from about 0.7 to about 1.1 W/W % of mecoprop-P.

More preferable compositions comprise isoxaben; 2,4-D; mecoprop-P, anddicamba. These compositions preferably comprise from about 0.2 to about25 W/W % of isoxaben; from about 0.05 to about 35 W/W % of 2,4-D; fromabout 0.05 to about 20 W/W % of mecoprop-P, and from about 0.01 to about25 W/W % dicamba. More preferably, these compositions comprise fromabout 2 to about 3 W/W % of isoxaben; from about 3 to about 5 W/W % of2,4-D; from about 0.1 to about 1 W/W % of mecoprop-P; and from about 0.1to about 0.8 W/W % of dicamba. Most preferably, these compositionscomprise from about 2.4 to about 2.9 W/W % of isoxaben; from about 3.50to about 4.32 W/W % of 2,4-D; from about 0.7 to about 1.1 W/W % ofmecoprop-P; and from about 0.4 to about 0.5 W/W % of dicamba.

The presently disclosed compositions can be present both as mixedformulations of the components, if appropriate with other activecompounds, additives and/or customary formulation auxiliaries, which arethen applied in a customary manner diluted with water, or be prepared asso-called tank mixes by joint dilution of the separately formulated orpartially separately formulated components with water.

The compositions disclosed herein can be formulated in various waysdepending on the prevailing biological and/or chemico-physicalparameters. Examples of suitable formulation options are: wettablepowders (WP), emulsifiable concentrates (EC), aqueous solutions (SL),emulsions (EW), such as oil-in-water and water-in-oil emulsions,sprayable solutions or emulsions, oil- or water-based dispersions,suspoemulsions, dusts (DP), seed-dressing compositions, granules forbroadcasting and soil application, or water-dispersible granules (WG)1ULV formulations, microcapsules or waxes.

Based on these formulations it is also possible to produce combinationswith other pesticidally active substances, such as other herbicides,fungicides or insecticides, and also with safeners, fertilizers and/orgrowth regulators, for example in the form of a ready-mix or tank mix.

Wettable powders are preparations which are uniformly dispersible inwater and which contain, in addition to the active compound and as wellas a diluent or inert substance, surfactants of ionic or nonionic type(wetting agents, dispersants), for example polyethoxylated alkylphenols, polyethoxylated fatty alcohols, polyethoxylated fatty amines,alkanesulfonates, alkylbenzenesulfonates, sodium ligninsulfonate, sodium2,2′-dinaphthylmethane-6,61-disulfonate, sodiumdibutylnaphthalene-sulfonate or else sodium oleoylmethyltaurinate.

Emulsifiable concentrates are prepared by dissolving the active compoundin an organic solvent, for example butanol, cyclohexanone,dimethylformamide, xylene or else relatively high-boiling aromaticcompounds or hydrocarbons with the addition of one or more surfactantsof ionic or nonionic type (emulsifiers). Examples of emulsifiers whichcan be used are calcium alkylarylsulfonates, such as Cadodecylbenzenesulfonate, or nonionic emulsifiers, such as fatty acidpolyglycol esters, alkylaryl polyglycol ethers, fatty alcohol polyglycolethers, propylene oxide-ethylene oxide condensation products, alkylpolyethers, sorbitan fatty acid esters, polyoxyethylene sorbitan fattyacid esters or polyoxyethylene sorbitan esters.

Dusts are obtained by grinding the active compound with finely dividedsolid substances, for example talc, natural clays, such as kaolin,bentonite and pyrophyllite, or diatomaceous earth.

Granules can be prepared either by spraying the active compound ontoadsorptive, granulated inert material or by applying active-compoundconcentrates to the surface of carriers such as sand, kaolinites orgranulated inert material, by means of adhesive binders, for examplepolyvinyl alcohol, sodium polyacrylate or else mineral oils. Suitableactive compounds can also be granulated in the manner which is customaryfor the preparation of fertilizer granules, if desired as a mixture withfertilizers. Water-dispersible granules are generally prepared byprocesses such as spray-drying, fluidized-bed granulation, diskgranulation, mixing using high-speed mixers, and extrusion without solidinert material.

The agrochemical formulations generally contain from 0.1 to 99% byweight, in particular from 2 to 95% by weight, of active compounds, thefollowing concentrations being customary, depending on the type offormulations: In wettable powders the concentration of active compoundis, for example, from about 10 to 95% by weight, the remainder to 100%by weight consisting of customary formulation constituents. Inemulsifiable concentrates the concentration of active compound can be,for example, from 5 to 80% by weight. Formulations in the form of dustsusually contain from 5 to 20% by weight of active compound, whilesprayable solutions contain from about 0.2 to 25% by weight of activecompound. In the case of granules, such as dispersible granules, thecontent of active compound depends partly on whether the active compoundis in liquid or solid form and on which granulation auxiliaries andfillers that are used. In water-dispersible granules the content isgenerally between 10 and 90% by weight.

In addition, said formulations of active compound may comprise thetackifiers, wetting agents, dispersants, emulsifiers, preservatives,antifreeze agents and solvents, fillers, colorants and carriers,antifoams, evaporation inhibitors, pH and viscosity regulators,thickeners and/or fertilizers which are customary in each case.

For use, the formulations, which are in commercially available form,are, if appropriate, diluted in a customary manner, for example usingwater in the case of wettable powders, emulsifiable concentrates,dispersions and water-dispersible granules. Preparations in the form ofdusts, soil granules, granules for spreading and sprayable solutions areconventionally not diluted any further with other inert substances priorto use.

EXAMPLES Example 1

Formulation of the Four-Way Isoxaben-2,4-D-Mecoprop-P-Dicamba Herbicide.Isoxaben is a water insoluble compound, while 2,4-D, mecoprop-P, anddicamba all are water soluble. Incorporating water-insoluble activeingredients with water soluble inactive ingredients can be problematic.To address this, a fine particulate suspension of isoxaben was createdin an aqueous solution by using a polymeric suspension aide. Briefly,mecoprop-P and dicamba were converted to potassium salts, then added toan aqueous solution along with a 2,4-D DMA salt. Isoxaben was wet milledto obtain fine-milled insoluble isoxaben particulates, although othermethods of milling can be used interchangeably, for example, dry millingand air milling. The isoxaben particulates were then physicallystabilized by adding a polymeric suspension aide and adjusting the pH ofthe solution. Polymeric suspension aides and methods of use are wellknown in the art. Further, other thickening agents are well known in theart and can be used to the same effect.

Example 2

Calculation of Pre-Emergent Synergism at Full Label Rate.

As a first test, a four-way aqueous suspension comprising isoxaben;2,4-D; mecoprop-P, and dicamba was made according to Example 1 at theconcentrations set forth in Table 1 and tested for pre-emergentsynergism.

TABLE 1 AI Dosage Transformed Transformed No. Description Conc. DosageUnit Dosage Dosage Unit 1 UNTREATED UNTREATED 2 Isoxaben Only 2.65 549.6G A/HA 6.4 OZ/1000 FT2 ISOXABEN 2.65 549.6 3 No Isoxaben 6.11 1301 GA/HA 6.4 OZ/1000 FT2 2,4-D AS SALT 4.73 1007 MECOPROP-P 0.94 200.2DICAMBA .44 93.7 4 4-Way pre/post composition 7.97 1700 G A/HA 6.4OZ/1000 FT2 ISOXABEN 2.65 565 2,4-D 3.94 840 MECOPROP-P .94 200.5DICAMBA .44 93.85

To test for synergism, broadleaf weed seeds were planted in threereplicates of 10 m² plots for each of four conditions: (1) untreated;(2) containing isoxaben only; (3) containing post-emergent herbicidesonly; and (4) containing a four-way pre/post composition. The plots werethen treated with the respective solutions at the rate set forth inTable 1 immediately upon planting and three additional times afterward.Plots were then rated for percent suppression as compared to control.Expected control was approximated by using Gowing's calculation:E=X+Y−XY/100,where

E=Expected % Control of Herbicides A+B,

X=Observed % Control of Herbicide A, and

Y=Observed % Control of Herbicide B.

The data was then analyzed as follows:

Synergism: Observed control > Expected control Neutral: Observed control= Expected control Antagonism: Observed control < Expected control

As can be seen at FIG. 1, synergism was observed for the 4-way pre/postformulation for black medic alone; buckhorn plantain alone; white cloveralone; and the mix of black medic, clover, dandelion, henbit, pigweed,purslane, red clover, and spurge.

Example 3

Calculation of Pre-Emergent Synergism at One-Half and One-Fifth FullLabel Rate.

Example 2 was repeated using the same compositions, only at doses ofone-half and one fifth of the transformed dosage set forth in Table 1.As can be see in FIG. 2, synergism was observed at the one-halftransformed dosage for all of the weed mixes tested. Synergism also wasobserved at the one-fifth transformed dosage for buckhorn plantain andwhite clover.

Example 4

Calculation of Post-Emergent Synergism at Full Label Rate.

A four-way aqueous suspension comprising isoxaben; 2,4-D; mecoprop-P,and dicamba was made according to Example 1 at the concentrations setforth in Table 1. A test field was then subdivided into three replicatesof 10 m² plots for each of four conditions: (1) untreated; (2)containing isoxaben only; (3) containing post-emergent herbicides only;and (4) containing a four-way pre/post composition. Broadleaf weeds wereidentified and tallied in each plot. The plots were then treated withthe respective solutions at the rate set forth in Table 1. Threeadditional treatments were made thereafter. Data were taken at 1, 3, and7 days and 2, 3, 4, and 8 weeks after the initial application andanalyzed as in Example 2. As can be seen at FIG. 3, synergism wasobserved for black medic; white clover; and a mix of false dandelion,plantain, rabbitfoot clover, and white clover.

Example 5

Calculation of Post-Emergent Synergism at One-Half and One-Fifth FullLabel Rate.

Example 4 was repeated using the same compositions, only at doses ofone-half and one fifth of the transformed dosage set forth in Table 1.As can be see in FIG. 4, synergism was observed at the one-fifth ratefor white clover.

What is claimed is:
 1. A herbicidal composition, comprising at least onepre-emergent herbicide and at least two post-emergent herbicides,wherein the herbicidal composition comprises amounts of the pre-emergentherbicide and the post-emergent herbicides effective to inhibit both (i)pre-emergent and (ii) post-emergent development of a weed, wherein theat least one pre-emergent herbicide comprises the active ingredientisoxaben, and wherein the at least two post-emergent herbicides comprise2,4-D and mecoprop-P, wherein the composition further comprises dicamba,and wherein the herbicides in the composition consisting of isoxaben,2,4-D, mecoprop-P and dicamba, wherein the composition comprises fromabout 0.2 to about 25 W/W % of the isoxaben; from about 0.05 to about 35W/W % of the 2,4-D; from about 0.05 to about 20 W/W % of the mecoprop-P;and from about 0.01 to about 25 W/W % of the dicamba.
 2. The herbicidalcomposition of claim 1 comprising: from about 2 to about 3 W/W % of theisoxaben; from about 3 to about 5 W/W % of the 2,4-D; and from about 0.1to about 1 W/W % of the mecoprop-P.
 3. The herbicidal composition ofclaim 1 comprising: from about 2.4 to 2.9 W/W % of the isoxaben; fromabout 3.50 to about 4.32 W/W % of the 2,4-D; and from about 0.7 to about1.1 W/W % of the mecoprop-P.
 4. The herbicidal composition of claim 2comprising from about 0.1 to about 0.8 W/W % of the dicamba.
 5. Theherbicidal composition of claim 3 further comprising from about 0.4 toabout 0.5 W/W % of dicamba.
 6. A method of controlling weed growth, saidmethod comprising applying a composition comprising at least onepre-emergent herbicide and at least two post-emergent herbicides to aweed or seed thereof or to a field where the weeds are expected to grow,wherein the composition comprises amounts of the pre-emergent herbicideand the post-emergent herbicides effective to inhibit both (i)pre-emergent and (ii) post-emergent development of a weed, wherein theat least one pre-emergent herbicide comprises the active ingredientisoxaben, and wherein the at least two post-emergent herbicides comprise2,4-D and mecoprop P, wherein the composition further comprises dicamba,and wherein the herbicides in the composition consisting of isoxaben,2,4-D, mecoprop-P and dicamba, wherein the composition comprises fromabout 0.2 to about 25 W/W % of the isoxaben; from about 0.05 to about 35W/W % of the 2,4-D; from about 0.05 to about 20 W/W % of the mecoprop-P;and from about 0.01 to about 25 W/W % of the dicamba.
 7. The method ofclaim 6 wherein the weed is selected from the group consisting of:plantain, including buckhorn plantain; clover, including white clover,red clover, and rabbitfoot clover; black medic; dandelion; henbit;pigweed; purslane; spurge; false dandelion; ground ivy; wild garlic;wild onion; and wild violet.
 8. The method of claim 6, comprising: fromabout 2 to about 3 W/W % of the isoxaben; from about 3 to about 5 W/W %of the 2,4-D; and from about 0.1 to about 1 W/W % of the mecoprop-P. 9.The method of claim 6, comprising: from about 2.4 to 2.9 W/W % of theisoxaben; from about 3.50 to about 4.32 W/W % of the 2,4-D; and fromabout 0.7 to about 1.1 W/W % of the mecoprop-P.